1. Field of the Invention
The present invention relates to a self-sealing cannula assembly used in insufflatory surgery.
2. Background of the Invention
Various types of cannula assemblies have been provided with valves for maintaining a certain gas pressure in a body cavity during insufflatory surgery. Insufflatory surgery involves filling a body cavity with pressurized gas to maintain the cavity under a certain predetermined pressure. A conventional technique of performing the surgery is to first puncture the skin in a predetermined region of the body cavity with a needle including a stylet, and introducing an insufflatory gas into the body cavity.
A trocar is inserted into the bore of the cannula with a sharpened portion extending from the end of the cannula. The protruding end of the trocar is used to enable the end of the cannula to enter the body cavity through an incision made by the trocar in a different locality of the pressurized body cavity. The trocar may then be removed from the cannula. Surgical instruments may be inserted through the cannula to permit required endoscopic procedures. Because the body cavity is under pressure, escapement of the insufflatory gas must be prevented during insertion of the instruments and while the surgical procedure is being performed.
The prior art contains various types of cannula assemblies provided with valves for maintaining gas pressure in the body cavity when the trocar or other surgical instruments are inserted and removed from the cannula.
Of primary interest to the present invention is an assembly disclosed in U.S. Pat. No. 4,177,814, wherein there is disclosed a self-sealing cannula which maintains insufflation pressure in a body cavity by means of a slotted elastomeric valve positioned in a valve seat with the slots disposed over the cannula valve passage. Separate means are provided to compress the valve against a valve seat to seal the slot or slots.
Other patented cannula assemblies designed to maintain gas pressure within a body cavity include U.S. Pat. No. 3,853,127, which discloses a certain type of perforation formed in an elastic sealing member.
U.S. Pat. No. 3,994,287 discloses an assembly wherein gas pressure is maintained by means of a flexible ring having an aperture positioned within an annular valve seat. A collar is placed over the ring to seal the sidewalls of the valve seat. The disclosed assembly unfortunately loses it seal when the surgeon removes the instrument, and other sealing means must be provided to maintain gas pressure.
Another cannula assembly is disclosed in U.S. Pat. No. 3,989,049, wherein a trumpet valve is used to maintain pressure. Here, the trumpet valve must be manually regulated by the surgeon while removing the trocar and replacing it with another instrument, such as a laparoscope.
U.S. Pat. No. 5,041,095 discloses a hemostasis valve to prevent blood leakage. This valve assembly utilizes a snap-on cap which houses at least a pair of separate discs, each having slots for receiving a catheter to prevent backflow of blood.
Another device for introducing a catheter into a body for diagnosis or treatment, as in the case of a vascular balloon catheter, a catheter for angiography or other need for insertion into a blood vessel is shown and described in U.S. Pat. No. 5,092,846.
A seal for use with a cannula assembly is disclosed in U.S. Pat. No. 5,104,383. This disclosure is directed principally to a stabilizer plate to limit the eccentric movement of an instrument relative to the seal, which may inadvertently release the gaseous seal.
A hemostasis valve formed of a longitudinally extended valve housing is disclosed in U.S. Pat. No. 5,114,408. An apertured cap is provided for enclosing a first opening of the housing. The cap permits insertion of a catheter.
U.S. Pat. No. 5,122,122 discloses a trocar sleeve provided in a relatively complicated assembly requiring an expanded end of the trocar sleeve in abutting relationship with the inner surface of the abdominal cavity.
A particular configuration of slits formed in a self-sealing gasket for a catheter was disclosed in European Patent Publication 0 344 907 A2.
It is an object of the present invention to provide a cannula assembly having positive sealing during entry, use and substitution of surgical instruments and removal of a surgical instruments during the performance of a surgical procedure.
It is among the various objects of the invention to provide a single cap of an elastomeric material, such as silicone, in which the inner circumferential wall surface is provided with a plurality of axially spaced grooves adapted to be received by interfitting, axially spaced lands formed in the outer circumferential wall of an enlarged cuplike portion of a cannula.
It is another object of the present invention to provide a single sealing member for a cannula assembly to thereby eliminate the need for an additional compressing retainer member requiring machined threads and other machined surfaces to receive and compress a sealing valve to thereby insure sealing requirements in prior devices.
It is a further object of this invention to provide a cannula configuration which permits several variations of elastomeric gas-sealing caps or valves adaptable for use with inserted instruments of varying diameters and configurations.
A still further object of this invention is to provide an additional elastomeric adaptor cap to be received by the external surface of a first self-sealing elastomeric cap, whereby the outer cap has a sealing opening for an instrument of relatively small diameter and without requiring removal of the first cap during surgery and which will maintain the seal of the cannula assembly.